← Back to Blog · 2026-10-04 · 7 min read · Strategy Case Study

Picture this: it's early May 2021, and rebar futures on the Shanghai Futures Exchange are printing levels that would have sounded absurd a year earlier. Steel mills are running flat out, mill margins are fat, and every momentum account in Asia is long. Then, almost overnight, the market turns on a headline — not a chart pattern, not a liquidity event, but a government statement. Weeks of gains get unwound in days.

If you trade Chinese commodity futures, that episode is required reading. Not because rebar will repeat 2021 exactly, but because it compresses nearly every lesson a trend follower needs into one year: how powerful a genuine supply-side trend can be, and how brutally policy can interrupt it. Let's walk through it.

A Quick Primer: What You're Actually Trading

Before the history, the mechanics — because sizing and risk decisions mean nothing without them.

• Rebar (RB): listed on the Shanghai Futures Exchange (SHFE). The contract is 10 metric tons per lot, with a minimum tick of 1 yuan per ton — so one tick moves your P&L by 10 RMB per lot. That's a small tick value by global standards, which makes rebar accessible for smaller accounts, but don't let that fool you into oversizing.
• Iron ore (I): the upstream cousin, on the Dalian Commodity Exchange (DCE). 100 tons per lot, tick of 0.5 yuan per ton. Note that foreign traders' direct access to iron ore has historically been more restricted than to SHFE products — many international traders get iron ore exposure indirectly through rebar and related spreads.
• Hours: day sessions plus a night session (roughly 21:00 to 23:00 for rebar). That night session matters — it's where Chinese markets digest offshore moves before the day session opens.

One more structural note: Chinese exchanges use exchange-set margin ratios that regulators can and do adjust during volatile periods. When things get hot, margins go up. Build that into your risk model from day one.

The Setup: Why Steel Went Vertical in 2021

The 2021 rally wasn't a liquidity fantasy — it had a real, legible supply story.

China had pledged to peak carbon emissions before 2030, and steel production was squarely in the crosshairs. Through the first half of the year, authorities pushed production restrictions in key steelmaking regions, with Tangshan — one of the country's largest steel-producing cities — under particularly tight controls. The message from Beijing was unusually explicit: crude steel output in 2021 should not exceed 2020 levels.

At the same time, demand was strong. The post-COVID recovery, both in China and globally, kept construction and manufacturing demand robust. So you had the classic trend-follower's dream: constrained supply meeting healthy demand, with a policy tailwind that everyone could read in the news. Rebar futures rallied hard through the first months of 2021 and pushed into record territory around May, with iron ore climbing alongside it.

For a simple trend system — say, a breakout or moving-average model — this was the kind of market that pays for a year of small losses. Long entries triggered repeatedly, and the trend kept confirming.

The May Shock: When the Trend Meets the State

Then came the lesson.

By mid-May 2021, with commodity prices surging across the board, Chinese authorities intervened — verbally first, then practically. Statements from top economic officials warned against commodity speculation and hoarding, and regulators moved to curb excessive speculation. The effect on steel and iron ore was immediate: a sharp, violent correction that erased a large chunk of the rally in a matter of days. This wasn't a slow rollover you could exit gracefully on a 20-day breakout. It was a gap-and-go-down environment.

The market then did something equally instructive: after the shakeout, steel prices staged a second leg higher later in the summer, this time amplified by the broader energy crunch. Thermal coal futures — a story every trader now knows — went on one of the most extreme rallies in Chinese commodity futures history in 2021, roughly multiplying several times over before authorities stepped in again around October with aggressive intervention that crushed the coal complex in short order. Steel followed the complex down.

So 2021 gave you, in sequence:

1. A policy-driven supply trend that trend followers could ride for months.
2. A policy-driven crash that punished anyone who treated the trend as permanent.
3. A second trend leg that rewarded those who re-engaged.
4. A final policy-driven collapse that punished anyone still married to the trade.

If you only remember one thing: in Chinese commodity futures, policy is not an exogenous risk you can ignore. It is a core input to the trend itself.

Lesson One: Size for Gaps, Not for ATR

Most retail traders size positions using average true range or a fixed percent-stop. That works — until a policy headline turns your 1.5% stop into a 6% loss because the market gapped through it at the open.

During both the May and October 2021 interventions, limit-move days and gapping opens were live risks. On Chinese futures, daily price limits exist (and exchanges have widened or adjusted them during stress periods), but a limit move in your favor today can become a limit move against you tomorrow with no exit in between.

Practical rules that survived 2021:

• Halve your normal size when a trade's thesis depends on government policy continuing unchanged. A policy-driven trend deserves policy-aware sizing.
• Assume your stop can slip by 2-3x in Chinese commodities during intervention periods. If that slippage blows through your per-trade risk budget, the position was too big.
• Track exchange margin announcements as part of your routine. When an exchange raises margin on a contract you hold, it's often a signal that regulators see the move as excessive.

Lesson Two: Respect the Headline Cycle

Trend followers love to say they ignore the news. In China, that's a luxury you can't afford. The pattern in 2021 repeated what traders had seen before — and would see again in the coal market that autumn: parabolic price action invites state intervention.

You don't need to predict the intervention. You need to recognize the conditions that make one likely:

• Price up several multiples in under a year on a contract central to industrial policy.
• State media running stories about speculation, hoarding, and input costs squeezing downstream manufacturers.
• Exchange margin hikes and fee adjustments stacking up.

When two or three of those line up, the rational move isn't to exit your trend — it's to stop adding, tighten risk, and take partial profits. Trend followers rarely go broke riding a trend; they go broke adding to a trend the government has already flagged.

Lesson Three: Re-Engagement Is Where the Money Was

Here's the part most traders got wrong. After the May correction, the obvious emotional response was "the trend is dead, policy killed it, I'm done." But the summer rally was arguably the cleaner, more sustained leg — and a disciplined re-entry system captured it.

The takeaway: your trend model needs symmetrical re-entry rules. If a stop-out or correction knocks you out, define in advance what brings you back in — a new breakout above a defined level, a higher-timeframe trend filter turning back on, a pullback-and-resume pattern. Traders who had this written down caught the second leg. Traders who traded on feelings sat out the best part of the year.

Lesson Four: Rebar and Iron Ore Are One Trade — Until They Aren't

Steel and its raw materials usually move together, but the 2021 production-cut story hit them differently. Cutting steel output is bearish iron ore demand and can be bullish steel prices (less supply) — a spread dynamic that played out at various points during the year. Traders who lumped rebar and iron ore into one "steel complex" risk bucket learned that the production-cut theme could make them partially offsetting, not doubly exposed.

If you trade both, define your correlation assumption explicitly and revisit it when the policy narrative shifts. In China, the reason prices move changes the relationship between prices.

Putting It Into Practice: A Simple Policy-Aware Trend Framework

Here's a stripped-down framework that reflects the lessons above. It's not a holy grail — it's a starting point you should test and adapt.

• Entry: N-day breakout (e.g., 20-day) in the direction of a longer-term filter (e.g., price above the 60-day average), on rebar or another liquid Chinese commodity contract.
• Sizing: risk a fixed small fraction of equity per trade, calculated on stop distance plus a gap buffer of 2x normal slippage.
• Policy overlay: if two or more intervention signals are flashing (parabolic move, state media pressure, margin hikes), cut size by half and stop adding.
• Exit: opposite-side breakout stop, with an additional hard de-risking rule after any single day that gaps against you beyond your buffer.
• Re-entry: predefined and mechanical — no discretionary "waiting for confirmation" that never ends.

None of this is exotic. The edge in 2021 wasn't a secret indicator; it was surviving the May shock with capital intact and having the rules to get back in by summer.

Test It Before You Trust It

Every trader has a story about a market like 2021 rebar — the trend that made the year, or the headline that broke it. The difference between the traders who profit from the next one and those who merely watch it is boring: backtesting on real data, honest position sizing, and rules written down before the headline hits.

If you're building or refining a system for Chinese commodity futures, it's worth pressure-testing it against real historical data before risking capital — and that's exactly what you can do through a futures evaluation on XS Select, with evaluations starting from $29. Whether your model would have survived May 2021 is a question better answered in a simulated account than in a live one.

The 2021 rebar run is over. The next policy-driven trend in Chinese futures is not a matter of if — only when. Trade it with rules.